Systems to drive aircraft autonomously without operation of aircraft main engines or tow vehicles during ground travel have been proposed and are being developed as “green” or electric taxi systems. One or more aircraft nose or main landing gear wheels are powered by a power source other than the aircraft's main engines to move the aircraft during ground operations. The aircraft landing gear drive wheels in proposed green taxi systems may be powered by hydraulic or pneumatic motors, as well as by electric drive motors, although primary development efforts have focused on electric taxi systems. When these autonomous aircraft taxi systems have been approved by regulatory authorities for installation and use, it is unlikely that all aircraft will have the systems installed and in operation immediately following their approval. Airport ground operations procedures will differ for aircraft moved by electric taxi systems and for aircraft moved by their main engines and by tow vehicles. Consequently, to maintain efficient airport ground operations and avoid delays in aircraft turnaround, a quick and easy way to identify which aircraft are autonomously driven by electric taxi systems and which aircraft are not is needed.
A range of aircraft wheel drive systems has been proposed in the art. U.S. Pat. Nos. 7,445,178 to McCoskey et al; 8,109,463 to Cox et al.; 8,684,300 to Wilson et al.; and U.S. Patent Application Publication Nos. 2009/0294577 to Rogues et al.; 2010/0065678 to Kiyosawa; and 2010/0276535 to Charuel et al are illustrative of various drive systems intended to move aircraft autonomously on the ground. None of these systems, however, suggests any type of apparatus, method, or system specifically designed to identify aircraft that are equipped with the wheel drive systems described therein. Airport ground or control tower personnel viewing the aircraft exterior would not be able to distinguish such wheel drive system-equipped aircraft capable of autonomous ground movement from aircraft that require tow vehicles and operation of main engines for ground movement. Direct communication between an aircraft pilot or cockpit crew and airport personnel is required to confirm the mode of ground movement and what is needed from airport personnel to guide the aircraft's movement in the airport ramp area. Establishing effective direct communication in a congested airport ramp and gate area may be problematic.
Aircraft are usually identified by airline names and logos and/or identifying information on the fuselage exterior. This identifying information does not provide information relating to whether the aircraft is equipped with an electric taxi system, however. Even if it did, such information is not clearly visible at all times when an aircraft is traveling on the ground. Identifying indicia that are clearly and easily visible from a distance are not typically used on or in connection with aircraft landing gear wheels. Systems for enhancing the visibility and appearance of other vehicle wheels have been proposed. U.S. Pat. Nos. 4,381,537 to Hinrichs and 7,101,066 to Bond and U.S. Patent Application Publications Nos. 2003/0223243 to Miller and 2004/0257825 to Choi et al are examples of systems that use arrangements of lights for decoration or illumination on automobile wheels. The Hinrichs system is directed to producing an illusion of movement whether a wheel is rotating or not, and the Bond system uses rechargeable batteries that turn wheel lighting on when the vehicle starts and off when the vehicle is turned off. The Miller system, while primarily decorative and intended to customize an owner's automobile, acknowledges that the lighted wheel described can be seen more clearly at night or in bad weather. The Choi et al system, which is stated to improve safety as well as the appearance of a vehicle, generates electricity to power wheel lighting through the rotation of an axle on which the wheel is mounted. These systems may work well to make automobile wheels more decorative or easily seen, but the structural and functional arrangements described would not translate effectively to an aircraft landing gear wheel environment to identify or enhance the visibility of a drive wheel to identify an aircraft driven with an electric or green taxi system during airport ground operations.
A need exists, therefore, for an aircraft identification system and method for quickly and easily identifying to airport personnel and to flight crews driving aircraft during ground operations which aircraft are equipped with pilot-controlled electric taxi or other green taxi systems for autonomous ground movement while these aircraft are preparing for pushback and driven during pushback and taxi on airport ground surfaces to distinguish them from aircraft are not equipped with such taxi systems. When airport personnel are able to clearly distinguish aircraft equipped with electric taxi systems from aircraft that are not, the requisite ground support services can be efficiently and safely provided for all aircraft using these services at an airport.